It is common for babies to have breast lumps or swelling under the nipple. They are almost always benign and due to exposure to maternal estrogen in the womb. The lump generally goes away on its own and usually no treatment is required. I would suggest that you do not touch or pinch the area which may cause inflammation. If the nipple appears to be swollen and looks infected or has a discharge and your baby has fever, call your pediatrician for an appointment to rule out infection.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.